The basic process for the formation and development of images on the surface of photoconductive materials by electrostatic means entails placing a uniform electrostatic charge on a photoconductive insulating layer known as a photoconductor or photoreceptor, exposing the photoreceptor to a light and shadow image to dissipate the charge on the areas of the photoreceptor exposed to the light, and developing the resulting electrostatic latent image by depositing on the image a finely divided electroscopic material known as toner. Toner typically comprises a resin and a colorant. The toner will normally be attracted to those areas of the photoreceptor which retain a charge, thereby forming a toner image corresponding to the electrostatic latent image. This developed image may then be transferred to a substrate such as paper. The transferred image may subsequently be permanently affixed to the substrate by heat, pressure, a combination of heat and pressure, or other suitable fixing means such as solvent or overcoating treatment.
Numerous processes are available for the preparation of toners. Emulsion aggregation (EA) is one such method. Emulsion aggregation toners can be used in forming print and/or xerographic images. Emulsion aggregation techniques can entail the formation of an emulsion latex of the resin particles by heating the resin, using emulsion polymerization, as disclosed in, for example, U.S. Pat. No. 5,853,943, the disclosure of which is totally incorporated herein by reference. Polyester EA ultra low melt (ULM) toners have been prepared utilizing amorphous and crystalline polyester resins as disclosed in, for example, U.S. Pat. No. 7,547,499, the disclosure of which is totally incorporated herein by reference.
Exemplary emulsion aggregation toners include acrylate based toners, such as those based on styrene acrylate toner particles as illustrated in, for example, U.S. Pat. No. 6,120,967, and polyester toner particles, as disclosed in, for example, U.S. Pat. Nos. 5,916,725 and 7,785,763 and U.S. Patent Publication 2008/0107989, the disclosures of each of which are totally incorporated herein by reference.
Many polymeric materials utilized in the formation of toners are based upon the extraction and processing of fossil fuels, leading ultimately to increases in greenhouse gases and accumulation of non-degradable materials in the environment. Energy and environmental policies, increasing and volatile oil prices, and public/political awareness of the rapid depletion of global fossil reserves have created a need to find sustainable monomers derived from biomaterials. By using bio-renewable feedstock, manufacturers can reduce their carbon footprint and move to a zero-carbon or even a carbon-neutral footprint. Bio-based polymers are also very attractive in terms of specific energy and emission savings. Using bio-based feedstock can decrease the amount of plastic targeted for landfills, help provide new sources of income for domestic agriculture, and reduce the economic risks and uncertainty associated with reliance on petroleum.
While known compositions and processes are suitable for their intended purposes, improved resins and toner compositions, including resins and toners derived from sources other than petroleum and/or from renewable resources, are desirable. There is also a need for toners derived from relatively inexpensive sources. In addition, there is a need for toners, such as emulsion aggregation toners, having the aforementioned advantages. Further, there is a need for emulsion aggregation toners derived either from petroleum-based sources or from renewable resources that can be obtained in high yield, have small particle size, have controlled particle morphology or shape, have a narrow particle GSD, and have a core-shell structure.